An organic light-emitting diode (OLED) is an active light-emitting device. Compared with a liquid crystal display which is a conventional display manner, the OLED can self-emit light without the use of a backlight. The OLED is formed by a thin organic film and a glass substrate, and the organic material emits light in response to an electric current. Therefore, an OLED display screen can save electric energy significantly, and can be made lighter and thinner than an LCD display screen. In addition, the OLED display screen can withstand a temperature change in a wider range and enable a wider viewing angle compared to the LCD display screen. Thus, the OLED is expected to be the next generation of panel display technology after the LCD, and is one of the most popular panel display technologies.
There are multiple color patterning technologies for the OLED screen, among which the relatively mature one is OLED evaporation technology which has been successfully applied in mass production of the OLED screens. The conventional RGB Stripe layouts are used in this technology for evaporation, and an RGB side-by-side manner creates the most satisfactory picture effect. In the side-by-side manner, three sub-pixels that are red, green, and blue (R, G, and B) sub-pixels exist in one pixel range. Each sub-pixel is a rectangle, and corresponds to an independent organic light-emitting device. The organic light-emitting devices are formed on their corresponding pixel positions on an array substrate by using a Fine Metal Mask (FMM) through evaporation film-forming technology, where the FMM is briefly referred to as an evaporation mask. Manufacturing of high-PPI (Pixel Per Inch) OLED display screens depends on fineness and good mechanical stability of the FMM and a pixel arrangement manner.
FIG. 1 is a schematic diagram of a pixel arrangement of an OLED display screen in the prior art. Such a pixel structure is usually called Real RGB in the field. As shown in FIG. 1, this OLED display screen uses a pixel side-by-side arrangement, and each pixel unit includes an R sub-pixel region 101, a G sub-pixel region 103, and a B sub-pixel region 105. The R sub-pixel region 101 includes an R light-emitting region 102 and an R non-light-emitting region. The G sub-pixel region 103 includes a G light-emitting region 104 and a G non-light-emitting region. The B sub-pixel region 105 includes a B light-emitting region 106 and a B non-light-emitting region. FIG. 1 shows that the R, G, and B sub-pixels are all rectangular and their light-emitting regions are identical in area, and the R, G, and B sub-pixels are arranged in a straight line. The light-emitting region of each sub-pixel region includes a cathode, an anode, and an electroluminescent layer (also referred to as an organic emission layer), where the electroluminescent layer is located between the cathode and the anode, and used for producing lights with predetermined colors to implement display. During preparation of the display screen, the evaporation process usually needs to be performed three times to form an electroluminescent layer with a particular color in a light-emitting region of a pixel region with the corresponding color.
An FMM shown in FIG. 2 is generally used for evaporation of the pixel structure of the OLED display screen shown in FIG. 1. The FMM includes a shielding region 107 and several evaporation openings 108, and a shielding region between two adjacent evaporation openings 108 in the same column is called a bridge. Because the sub-pixels with the same color in the arrangement manner of FIG. 1 longitudinally align, the corresponding evaporation openings 108 on the FMM necessarily align in the same way. However, this arrangement causes the bridge between two vertically adjacent evaporation openings 108 to have a risk of disconnection. Moreover, each evaporation opening 108 on the FMM needs to correspond to a predetermined pixel position. However, space for alignment between the openings on the FMM and the sub-pixel regions is narrowed according to the conventional pixel arrangement manner, which probably incurs lack of color, color mixture, or other defects.